1. Field of the Invention
The present invention relates to a discriminating apparatus for discriminating whether printed matter is an original or a reproduction, particularly, to a discriminating apparatus for discriminating a reproduction obtained by using a base material differing from an original in the color of the base material of the printed matter.
2. Description of the Related Art
In recent years, a color scanner or a color printer that is connected to a digital color copying machine or a computer has been widely propagated so as to make it possible to easily obtain a reproduction of printed matter. Also, the performance of these copying machine, color scanner and color printer has been prominently improved so as to make it difficult to discriminate between an original and a reproduction of printed matter. Under the circumstances, research is being conducted in an attempt to develop a discriminating apparatus for discriminating between an original and a reproduction of printed matter.
The conventional discriminating apparatus for discriminating between an original and a reproduction of printed matter utilizes in general the difference in the printing system between the two. To be more specific, the original of printed matter, e.g., authentic securities certificate, is printed in general by a relief press. On the other hand, a reproduction obtained by a copying machine or a printer is printed by dots of cyan (C), yellow (Y), magenta (M), black (K), etc. Generally, an authentic securities certificate has a high density region in which the substrate surface (non-printing region) and a printed surface (printing region) are arranged at a high density. If that high density region on the authentic securities certificate is irradiated with a light beam, a brightness pattern having large amplitude conforming to the printing pattern is generated in the light beam passing through or reflected from the particular high density region. However, if the corresponding region on a reproduction of the securities certificate is irradiated with the light beam, the amplitude of the brightness pattern of the light beam passing through or reflected from the particular high density region is diminished. Such being the situation, in the conventional discriminating apparatus as disclosed in, for example, Japanese Patent Disclosure (Kokai) No. 2003-323656, the brightness pattern is obtained by a detector in a prescribed resolution, and the discrimination between the authentic securities certificate and a reproduction is performed on the basis of the brightness pattern thus obtained.
However, in order to irradiate the substrate surface and the printing surface with light beams for obtaining the brightness pattern contained in the transmitted light beam or the reflected light beam on the surface, it is necessary for a printing pattern providing a key to the detection to be present. To be more specific, if the reading line of the brightness pattern deviates even slightly, the read brightness pattern is rendered quite different from the brightness pattern contained in the transmitted light beam or the reflected light beam.
Also, in another conventional discriminating apparatus as disclosed in Japanese Patent Disclosure No. 2003-323656 referred to above, it is necessary to suppress the fluttering or wrinkling of the printed matter to a level lower than the depth of the focal point at which sufficient resolution can be obtained in the portion where a printing pattern providing a key to the detection is present. It follows that high accuracy is required in the transfer device of the discriminating apparatus, so as to make it difficult to discriminate the printed matter at high speed. This difficulty does not provide a critical defect in the discriminating apparatus mounted to an apparatus not requiring the processing at high speed such as an ATM because the serviceability ratio of the discriminating apparatus section is low, though the processing rate of, for example, the ATM is lowered. However, it is difficult to use such a discriminating apparatus in a machine required to handle a large amount of printed matter for performing the discrimination between the original and a reproduction.
It should also be noted in conjunction with the conventional discriminating apparatus that, if fluttering or wrinkling is generated in the printed matter in a magnitude larger than the depth of the focal point, the erroneous discrimination is increased.